Weathering 01/05/ pgs IN: How is sediment/soil formed?

 Weathering - the breakdown of rock into smaller and smaller pieces. This is constantlyhappening!

 Mechanical  Chemical Types of Weathering

 Mechanical Weathering - the breakdown of rock by physical means. –Ice –Wind –Water –Gravity –Plants –Animals

 When water seeps into a crack in a rock and freezes it expands.  When it expands, it pushes against the sides of the crack, forcing it to open wider. Ice Wedging

 An enormous mass of moving ice. Glaciers

Glaciers Form when average temperatures are at or near freezing  Alpine glaciers create U-shaped valleys.  They push all the rock and sediment underneath them.

Rivers create V-Shaped valleys

Wind and Water

 Abrasion - the action of rocks and sediment grinding against each other and wearing away exposed surfaces. Wind and Water

Abrasion  When rocks grind against each other and wear away exposed surfaces.  Wind blows sand and dust against rocks.  Water in rivers and oceans cause rocks and sand to roll against each other.  Gravity causes rocks to fall

 Like ice wedging –Plants get into smaller cracks and as they grow they split the rock apart.

 Burrowing  Worms  Chemical Weathering

 Chemical Weathering - the chemical breakdown of rocks and minerals into new substances. –Water –Weak acids –Air –Soil

 Water causes many things to dissolve. –Even hard rock, like granite, is broken down by water.

 Acid rain is caused due to pollution.  Can cause very rapid weathering of rock.

 Breaks down limestone found underground –Forms caves

 Lichens produce organic acids that can slowly break down rock.

 Oxidation - a chemical reaction in which an element, such as iron, combines with oxygen to form an oxide.

 Water speeds up this process. –rust

Red Rock Canyon

OUT: Name three ways abrasion occurs in nature.